The present invention relates to machines for stapling the sheets of stacks of overlapping sheets to each other, and more particularly to improvements in so-called saddle stitching machines for signatures and the like. Still more particularly, the invention relates to improvements in saddle stitching or saddle-wire stitching machines of the type wherein a conveyor advances successive stacks of sheets along a straight path during each cycle of the machine and a reciprocable carriage supports one or more sets of tools which apply staples to successive stacks and thereupon deform the thus applied staples. The carriage is movable back and forth along the aforementioned straight path.
Saddle stitching machines of the above outlined character are disclosed, for example, in Swiss Pat. No. 337,177. The means for actuating the tools on the carriage includes cams or coulisses which are mounted in the frame of the saddle stitching machine. A drawback of heretofore known machines, including that which is disclosed in Swiss Pat. No. 337,177, is that their output remains unchanged irrespective of the dimensions of signatures or analogous accumulations of overlapping sheets. As a rule, the speed of the conveyor which transports successive signatures to the stitching station does not exceed two meters per second. On the other hand, the capacity of the apparatus (e.g., a gathering machine) which supplies signatures to the conveyor of the saddle stitching machine can be increased well beyond that of the just described stitching machine by the simple expedient of increasing the speed of the rotary drum-shaped gripper therein.